Article
Astronomy & Astrophysics
M. Giarrusso, M. Cecconi, R. Cosentino, M. Munari, A. Ghedina, F. Ambrosino, W. Boschin, F. Leone
Summary: In this study, the rotational periods of magnetic chemically peculiar stars of the main sequence were determined by measuring the variability of the integrated magnetic field modulus. New data on the periods of these stars were obtained, and a clear decrease in the field modulus of gamma Equ was observed.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
L. Freour, C. Neiner, J. D. Landstreet, C. P. Folsom, G. A. Wade
Summary: We conducted a spectropolarimetric analysis of the hot star V352 Peg. The analysis showed that the star is a chemically peculiar Bp star with overabundances of iron peak elements and underabundance of He and O. We detected a magnetic field in V352 Peg and determined its geometrical configuration through modelling and Zeeman-Doppler Imaging.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Eugene Semenko, Iosif Romanyuk, Ilya Yakunin, Dmitry Kudryavtsev, Anastasiya Moiseeva
Summary: We conducted a spectropolarimetric survey of 56 chemically peculiar (CP) stars in the Orion OB1 association and identified 31 magnetic stars. We found that the percentage of magnetic CP stars and the strength of their magnetic fields decrease with age. The average longitudinal magnetic field in the young subgroup OB1b is nearly three times stronger than in the older subgroups OB1a and OB1c. In the Orion Nebula, only 20% of CP stars have a magnetic field, which differs significantly from the nearby subgroup OB1c with 83% magnetic CP stars.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Z. Keszthelyi, A. de Koter, Y. Gotberg, G. Meynet, S. A. Brands, V Petit, M. Carrington, A. David-Uraz, S. T. Geen, C. Georgy, R. Hirschi, J. Puls, K. J. Ramalatswa, M. E. Shultz, A. ud-Doula
Summary: Magnetic fields have significant impact on the evolutionary models of massive stars, affecting mass-loss quenching, magnetic braking, and angular momentum transport. In this study, we use the MESA software to compute a grid of stellar structure and evolution models, taking into account the effects of surface fossil magnetic fields. By comparing the models with observations, we quantify the influence of different initial field strengths on the classification of stars and find that chemical mixing is less efficient in magnetic models due to rapid spin-down. We recommend comparing these models with spectropolarimetric and spectroscopic observations to further validate and constrain the magnetic field models.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
O. Kobzar, V Khalack, D. Bohlender, G. Mathys, M. E. Shultz, D. M. Bowman, E. Paunzen, C. Lovekin, A. David-Uraz, J. Sikora, P. Lampens, O. Richard
Summary: This study used TESS data to investigate the rotational periods of chemically peculiar stars, and found that the critical rotational fractions decrease with stellar age.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Z. Keszthelyi, G. Meynet, F. Martins, A. de Koter, A. David-Uraz
Summary: tau Sco is a magnetic B-type star with surprising characteristics such as slow rotation and nitrogen excess. To reconcile its properties with single-star models, an increase in the efficiency of rotational mixing and magnetic braking is necessary.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Chris Koen, Cole Johnston
Summary: Theta Car is a bright and well-studied B0 type star in a close binary system with an unseen companion, which has been extensively characterized at multiple wavelengths. Recent observations using the NASA TESS satellite show that the photometric variability of the star may be associated with surface brightness inhomogeneities.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Adam Griffiths, Patrick Eggenberger, Georges Meynet, Facundo Moyano, Miguel-A Aloy
Summary: This study explores the effects of the magneto-rotational instability (MRI) on the evolution of massive stars. The results show that the activation of MRI is highly sensitive to the treatment of meridional circulation and the existence of chemical gradients. The MRI efficiently transports matter and angular momentum, leading to noticeable differences in rotation rates and chemical structure of stars.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
S. P. Owocki, M. E. Shultz, A. ud-Doula, P. Chandra, B. Das, P. Leto
Summary: Magnetic B-stars exhibit circularly polarized radio emission that is related to magnetic field strength and stellar rotation rate. The acceleration of energetic electrons that emit the radio emission is found to be driven by centrifugal breakout (CBO) driven magnetic reconnection, challenging the conventional paradigm. This finding has significant implications for studying the magnetic field and rotation as well as other observed characteristics of B-stars.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
E. Paunzen, M. Prisegen
Summary: In this study, the possibility of detecting the characteristic 520 nm flux depression of magnetic chemically peculiar (mCP) stars using low-resolution BP/RP spectra was investigated. The results indicate that mCP stars can be clearly distinguished from normal-type objects, and the BP/RP spectra are qualified for efficiently searching for and detecting mCP stars.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
J. Labadie-Bartz, S. Huemmerich, K. Bernhard, E. Paunzen, M. E. Shultz
Summary: This study investigates the photometric variability of 1002 magnetic chemically peculiar (mCP) stars, determines their rotational periods, and identifies interesting objects for further studies. The results show that the rotation periods of the stars are related to their evolutionary stages, which supports the assumption of angular momentum conservation during the main-sequence evolution.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
N. Kharchenko, A. E. Piskunov, S. Hubrig, M. Schoeller
Summary: This study aims to establish the membership and evolutionary status of 11 chemically peculiar stars in the open cluster NGC 2516. By querying the Gaia EDR3 catalog, we identified 719 probable and 764 possible members among the 37,508 stars in the cluster region. We found that only 5 of the 11 considered chemically peculiar stars are highly probable cluster members.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
P. Petit, C. P. Folsom, J. -F. Donati, L. Yu, J. -D. do Nascimento, S. V. Jeffers, S. C. Marsden, J. Morin, A. A. Vidotto
Summary: In this study, observations of the active K2 dwarf E Eridani were reported based on SPIRou, NARVAL, and TESS data obtained over two months in late 2018. Fundamental parameters of the star were derived from visible and NIR wavelengths, revealing properties of the large-scale magnetic field and chromospheric emission. The photometric monitoring displayed clear signs of non-rotational evolution.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Iosif Romanyuk
Summary: This study presents important findings on the magnetic fields of chemically peculiar stars obtained through observations with the 6-m telescope, including the discovery of over 200 new magnetic chemically peculiar stars and the suggestion that their magnetic fields have a fossil nature. A new effective method for searching for magnetic stars based on ultra-accurate photometry data was developed.
Article
Astronomy & Astrophysics
Marcin Hajduk, Paolo Leto, Harish Vedantham, Corrado Trigilio, Marijke Haverkorn, Timothy Shimwell, Joseph R. Callingham, Glenn J. White
Summary: Chemically peculiar stars are upper main sequence stars with anomalies in their optical spectra, indicating peculiar chemical abundances of certain elements. Some of them exhibit strong magnetic fields, leading to non-thermal radio and X-ray emission from electrons in the ionising stellar wind traveling in the magnetosphere. Using LOFAR, radio emission from chemically peculiar stars was constrained in the frequency band 120-168 MHz, with results showing lower incidence rates at these frequencies.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Barnali Das, Poonam Chandra, Matt E. Shultz, Gregg A. Wade, James Sikora, Oleg Kochukhov, Coralie Neiner, Mary E. Oksala, Evelyne Alecian
Summary: This paper reports the discovery of eight new Main-sequence Radio Pulse emitters (MRPs), doubling the sample size of such objects. The study suggests that at least 32% of magnetic hot stars exhibit the observed Electron Cyclotron Maser Emission (ECME), indicating that this phenomenon is not rare. By analyzing a large sample, the authors propose an empirical relation to predict the likelihood of ECME in magnetic hot stars, with the maximum surface magnetic field strength and surface temperature playing a primary role. Furthermore, the influence of plasma density distribution on ECME pulse profiles is also presented.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
I. D. Berry, S. P. Owocki, M. E. Shultz, A. Ud-Doula
Summary: In this study, the photometric light curves of stars with centrifugal magnetospheres (CMs) are investigated. It is found that emission bumps can occur when the clouds of CM are projected off the stellar limb. Therefore, the findings of this study are important for understanding the formation mechanism of stellar light curves and for future magnetohydrodynamic simulations of CMs.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Robert Klement, Gail H. Schaefer, Douglas R. Gies, Luqian Wang, Dietrich Baade, Thomas Rivinius, Alexandre Gallenne, Alex C. Carciofi, John D. Monnier, Antoine Merand, Narsireddy Anugu, Stefan Kraus, Claire L. Davies, Cyprien Lanthermann, Tyler Gardner, Peter Wysocki, Jacob Ennis, Aaron Labdon, Benjamin R. Setterholm, Jean-Baptiste Le Bouquin
Summary: This study presents direct interferometric detections of the sdO companions of three Be stars and reveals first orbits and preliminary dynamical masses for two of the three Be+sdO systems. These results provide new fundamental parameters crucial for establishing the evolutionary status and origin of Be stars.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
S. P. Owocki, M. E. Shultz, A. ud-Doula, P. Chandra, B. Das, P. Leto
Summary: Magnetic B-stars exhibit circularly polarized radio emission that is related to magnetic field strength and stellar rotation rate. The acceleration of energetic electrons that emit the radio emission is found to be driven by centrifugal breakout (CBO) driven magnetic reconnection, challenging the conventional paradigm. This finding has significant implications for studying the magnetic field and rotation as well as other observed characteristics of B-stars.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
M. E. Shultz, S. P. Owocki, A. ud-Doula, A. Biswas, D. Bohlender, P. Chandra, B. Das, A. David-Uraz, V Khalack, O. Kochukhov, J. D. Landstreet, P. Leto, D. Monin, C. Neiner, Th Rivinius, G. A. Wade
Summary: Numerous magnetic hot stars exhibit gyrosynchrotron radio emission, and the radio luminosity is strongly dependent on rotation. By collecting and analyzing a large amount of data, it is found that there is a clear correlation between radio emission and rotation, and there is a close correlation between H alpha emission strength and radio luminosity. These results suggest that radio emission and H alpha emission may be produced by different mechanisms in centrifugal magnetospheres.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
P. Leto, L. M. Oskinova, C. S. Buemi, M. E. Shultz, F. Cavallaro, C. Trigilio, G. Umana, L. Fossati, I Pillitteri, J. Krticka, R. Ignace, C. Bordiu, F. Bufano, G. Catanzaro, L. Cerrigone, M. Giarrusso, A. Ingallinera, S. Loru, S. P. Owocki, K. A. Postnov, S. Riggi, J. Robrade, F. Leone
Summary: KQ Vel is a binary system with an unknown companion, and its radio emission may not originate from the magnetosphere of the Ap star, but could be related to its unknown companion. This places strict constraints on the orbital inclination of the KQ Vel stellar system.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Pierre Kervella, Simon Borgniet, Armando Domiciano de Souza, Antoine Merand, Alexandre Gallenne, Thomas Rivinius, Sylvestre Lacour, Alex Carciofi, Daniel Moser Faes, Jean-Baptiste Le Bouquin, Monica Taormina, Bogumil Pilecki, Jean-Philippe Berger, Philippe Bendjoya, Robert Klement, Florentin Millour, Eduardo Janot-Pacheco, Alain Spang, Farrokh Vakili
Summary: This study used multiple observation techniques to monitor the relative position of the Achernar system and estimate its orbital parameters and physical properties. The results showed that Achernar B orbits the primary Be star with a period of seven years, reaching a minimum distance of 2 astronomical units at periastron. The mass of the Be star was found to be approximately 6.0 times that of the Sun, while the mass of the secondary star was estimated to be approximately 2.0 times that of the Sun. The parameters of Achernar A were found to be in good agreement with the evolutionary model, making Achernar a valuable benchmark for studying fast rotators and intermediate mass binary star evolution.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Barnali Das, Poonam Chandra, Matt E. Shultz, Paolo Leto, Zdenek Mikulasek, Veronique Petit, Gregg A. Wade
Summary: Coherent radio emission via electron cyclotron maser emission (ECME) from hot magnetic stars was discovered more than two decades ago. Only recently was an empirical relation proposed to explain what makes a hot magnetic star capable of producing ECME. With the aim of testing the robustness of this relation, radio observations were conducted on five hot magnetic stars, resulting in the discovery of three more stars producing ECME. The proposed scaling relation remains valid after the addition of the newly discovered stars, but the correlation between magnetic field and effective temperature is only significant for a certain range of temperatures. The study concludes that both types of emission are powered by the same magnetospheric phenomenon, but the relationship with temperature varies for different types of stars.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
O. Kobzar, V Khalack, D. Bohlender, G. Mathys, M. E. Shultz, D. M. Bowman, E. Paunzen, C. Lovekin, A. David-Uraz, J. Sikora, P. Lampens, O. Richard
Summary: This study used TESS data to investigate the rotational periods of chemically peculiar stars, and found that the critical rotational fractions decrease with stellar age.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Z. Keszthelyi, A. de Koter, Y. Gotberg, G. Meynet, S. A. Brands, V Petit, M. Carrington, A. David-Uraz, S. T. Geen, C. Georgy, R. Hirschi, J. Puls, K. J. Ramalatswa, M. E. Shultz, A. ud-Doula
Summary: Magnetic fields have significant impact on the evolutionary models of massive stars, affecting mass-loss quenching, magnetic braking, and angular momentum transport. In this study, we use the MESA software to compute a grid of stellar structure and evolution models, taking into account the effects of surface fossil magnetic fields. By comparing the models with observations, we quantify the influence of different initial field strengths on the classification of stars and find that chemical mixing is less efficient in magnetic models due to rapid spin-down. We recommend comparing these models with spectropolarimetric and spectroscopic observations to further validate and constrain the magnetic field models.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
A. Ud-Doula, M. C. M. Cheung, A. David-Uraz, C. Erba, C. P. Folsom, K. Gayley, Y. Naze, C. Neiner, V Petit, R. Prinja, M. E. Shultz, N. Sudnik, J. S. Vink, G. A. Wade
Summary: The article discusses several ongoing space missions and instruments for UV spectropolarimetry, focusing on their capabilities to study the magnetic and plasma properties of hot stars. These studies aim to test the fundamental assumption that magnetospheres play a role in draining angular momentum and reducing mass-loss rate in stars.
ASTROPHYSICS AND SPACE SCIENCE
(2022)
Article
Astronomy & Astrophysics
C. P. Folsom, R. Ignace, C. Erba, R. Casini, T. del Pino Aleman, K. Gayley, K. Hobbs, R. Manso Sainz, C. Neiner, V Petit, M. E. Shultz, G. A. Wade
Summary: This article discusses the possibility of directly detecting stellar magnetic fields in the ultraviolet (UV) wavelengths and the potential of the proposed Polstar mission. It is found that UV observations are advantageous for studying wind resonance lines and photospheric lines in hot stars. The Zeeman effect combined with Least Squares Deconvolution is identified as potentially more effective for detecting photospheric magnetic fields in the UV, while the Hanle effect can provide complementary information in rapid rotators' photospheric lines and infer circumstellar magnetism in winds. A multi-line approach is crucial for inferring magnetic field properties.
ASTROPHYSICS AND SPACE SCIENCE
(2022)
Article
Astronomy & Astrophysics
M. E. Shultz, R. Casini, M. C. M. Cheung, A. David-Uraz, T. del Pino Aleman, C. Erba, C. P. Folsom, K. Gayley, R. Ignace, Z. Keszthelyi, O. Kochukhov, Y. Naze, C. Neiner, M. Oksala, V Petit, P. A. Scowen, N. Sudnik, A. Ud-Doula, J. S. Vink, G. A. Wade
Summary: Polstar is a proposed NASA space telescope that can provide high-resolution full-Stokes spectropolarimetry in the far ultraviolet and low-resolution linear polarimetry in the near ultraviolet. This telescope offers unique capabilities to study the magnetic and plasma properties of hot stars and test the fundamental hypothesis about their magnetospheres.
ASTROPHYSICS AND SPACE SCIENCE
(2022)
Article
Astronomy & Astrophysics
J. Labadie-Bartz, S. Huemmerich, K. Bernhard, E. Paunzen, M. E. Shultz
Summary: This study investigates the photometric variability of 1002 magnetic chemically peculiar (mCP) stars, determines their rotational periods, and identifies interesting objects for further studies. The results show that the rotation periods of the stars are related to their evolutionary stages, which supports the assumption of angular momentum conservation during the main-sequence evolution.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
I. D. Berry, M. E. Shultz, S. P. Owocki, A. ud-Doula
Summary: Early-type B stars with strong magnetic fields and rapid rotation form centrifugal magnetospheres. These magnetospheres can become optically thick enough for emission to occur via electron scattering. The magnetic and rotational properties of these stars can be inferred by comparing photometric modelling with spectropolarimetry data, but there are discrepancies between expected and observed values for optical depth.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)